Test set



C. A. ANDERSON Oct. 14, 1930.

- TEST SET Filed July 5, 1927 s sheets-shegt 1 C. A. ANDERSON TEST SET Filed July 5, 1927 3 Sheets-Sheet 2 Inu' Elm-inc! H; findersun Oct. 14, 1930.

Oct. 14, 1930. c. A. ANDERSON 7 TEST SET Filed July 5, 1927 3 Sheets-Sheet 3 Clarence Hfindarsmn I EYE- v ard well known type, having contacts suchv Patented Oct. 14,

UNITEDSTATES. PATENT OFFICE CLARENCE A. ANDERSON, OF CHICAGO, ILLINOIS, ASSICNOB, BY MESNE ASSIGNMENTS,

TO AMERICAN ELECTRIC COMPANY, OF DELAWARE OF CHICAGO, ILLINOIS, A CORPORATION TEST SET Application filed m a, 1927. Serial in. 203,054.

This invention relates to test sets for use in locating faults in transmission lines, especially telephone and telegraph transmission lines, and it is an object of this invention to produce a portable test set which shall be reliable in action, simple and rugged in construction, and which shall be economical of manufacture.

A feature of the invention consists in the novel circuit arrangement whereby a more reliable action is obtained. Another feature of the invention consists in the compact and expedient arrangement of the various parts whereby the test set is rendered more con venient to use. Additional features will be evident from the detailed description. -'Referring now to the drawings wherein there is illustrated an embodiment of my invention, Figure 1 is a diagram of the electrical circuit; Figure 2 is a perspective view of the set with a portion of the box broken/ away to show the arrangement on the inside thereof; Fi ure 3 is a -top view of the complete box with the cover open;v Figure 4 is a side view of the generator unit with the various parts mounted thereon; Figure 5 is a side View of the finder coil; Figure 6 is a front view partly in section of the finder coil; and Figure 7 is a section along the terminal clip of Fig. 6. I

Referring, now, to Fig. 1 of the drawings, 1 indicates a magneto generator of the standas 2, 3- and 4, arranged to be automatically operated in the well known manner upon the operation of the generator. In the'present case upon operating the generator the contacts 3 and 4 open and the contact 2 closes. Under those conditions the shaft 5 which is in electrical contact with one of the ter-I minals of the generator winding comes into electrical contact with left hand spring of contact 4. The generator is provided with a pair of interrupter contacts 23, arranged to closea moment after the voltage wave passes its peak during each half of the cycle. There is also-provided a number-of switches S S and S for establlshing various circuits for a purpose to be more fully described later.

'There is also provided an adjustable calibrated non-inductive resistance or rheostat 6, a telephone transmitter 7, an induction coil 8, battery 9, condenser 10, and signal lamp I 11. To the terminals 12 and 13 there is conconstructionofthefindercoil19,s owninFigsr 5, 6 and 7. The finder consists of an oblong coil having a core 31, and upper and lower ironpole' pieces 32 at the two ends of the coil, respectively. The coil 30 is fastened to the lower jaw of a spring clip by means of two screws which pass through the lower jaw of the clip and both pole pieces, the upper of which is threaded to receive the screws. The

spring clip is of a standard ty e in which the jaws 36 are held to ether y the tension of clampin springs 3 placed at each end of the clip. r iortions of the jaws 36 are extended at the rearto form handles 38, whereby the jaws ma be forced open by pivoting. a 0

at the ball earingls 39 a ainst the tension of s rings 37. T ere is ormed on each formed by depressing the metal of which the handle is made. This gives the handle rigidit against bending. The terminal leads from t e coil 30 are placed one in each groove,

on the lower handle portion, and extend to the cylindrical insulated terminal block 41. The spring clip is made of magnetic material and acts as a path for any flux that passes through the coil 30. ()n'the lower jaw of the clip there is provided a shield 40 which covers the lead wires from the coil 30 and protects them against dama e. The shield 40 is made of magnetic maternal and also improves the magnetic circuit at the meeting point of the upper and lower jaws of the clip. The terminal block 41 preferably comprises a tube of insulating material with the necessary fittings and is secured to the lower handle-38 side of t e center line of the handle a groove by means of two screws, one of which is 7 into which may be placed the conducting tip 5 the threaded hole 48.

of a standard cord, the same being then held in position by a screw which is passed through The other ends of the cord tip are. connected to the binding posts 14 and 15 shown in Fig. 1. The screws '42, for securing the terminal block to the clip,

pass through the tapped holes 42. It may be mentioned that the insulating tube and the three slugs 43, 44 and 45, together with the separatlng washers are preferably assembled before any holes are drilled, the drilling and tapping operations being performed on the assembled unit.

To use the finder 19, the upper jaw 36 is opened outwardly from the coil by forc- .ing the handles 38 together and the clip is passed over a wire which is to be tested. The

andles are then released and-the clip encircles the wire, assuming a position with re spect to the wire that is being-tested similar to the position of the clip shown in Fig. 2,

. with res ect .to the wire 22 shown in that figure. f alternating .current is passing through the wire encircled by the clip, the alternating field produced by the current will sass through the core 31 of coil 30, and inuce a voltage inthe coil. It is to be noted that .the clip provides a magnetic circuit an:

that field.

In making a test for ground one metallic circuit, the finder coil 1s left in its normal position. encircling the conductor. link 22 shown in Fig. 1, and one of the test CllPS for example clip 21, is connectedto a groun wire orother good ground connection and nating current from the generator, flowing through the link 22 will produce an alternating flux, and this alternating flux will induce an alternating voltage .in the: coil 30 of the finder 19. The finder 19 and the telephone receiver 18 being-connected in a loop which is closed at the contact 2-controlled by the generator shaft, an alternating current will flow in that loop and produce an audible sound in the telephone receiver. When, however, the line clip 20 is connected to the ungrounded line wire, then the previously traced circuit from the generator through the link 22 is open at the clip 20, and since no cur-rent is flowing through the link 22, no voltage is inducedin the coil of the finder 19 and no sound is heard in the telephone receiver. From-the above it may be seen that the presence or absence of a tone in the receiver indicates-whether the line conductor 5 connected with is or is not grounded.

As stated before, the intermittent closure of the contacts 23 occurs twice per cycle, a moment-after the peak of the output wave of the generator is reached. The closure of the contacts 23 resultsin the short circuiting of the generator 1 by way of the back contact of the switch S As a result. of the short circuiting of the generator there is provided a discharge path for the condenser 10 through the line that is being tested, said path extending from ground at'the remote end of the line, through the line to the clip den discharge 'of the condenser the other clip connected first to one line and then to the other. With each of the'two latter connections the lineman operates the generator. Upon operating the generator the contacts 3 and 4 open, the contact 2 closes, and a connection is'established'between the 5 of the generator. If the cli 20 happens to be connected to the line whic is grounded,

' a circuit is completed from ground at the far end of the line. over theline, to the clip 20, binding post 16, condenser 10., terminal 24 of the generator, throughthe generator winding to the frame of the generator, thence left hand spring of the contact 4 and the shaft f by way of the shaft 5 and left hand spring of contact 4, through the link 22, back contact controlled by the switch S binding post 17 to ground at the terminal clip 21. Alter- 20, left hand terminal of the condenser 10, backcontact of the switch S closed interator 1, left hand spring of contact 4, link 22, back contact controlled by the switch S to ground atthe terminal clip 21. This sudroduces a sharp peakin the current wave, w ich makes 10o rupter contacts 23, to the frame of the generfor maximum efliciency in the inductanceeffeet of the test current upon the finder coil 19. The line man having determined on which one of the lines the ground exists will now determine the approximate distance to the ground.- To do this the line man operates the generatorl and also the switch S The switch S in its 0 erated position substitutes the-variable cali rated vresistance'ti for the rounded line ina manner which is a parent rom the circuit shown in Fig. 1. I man observes-the intensity of the sound in the receiver, and if the sound is reater than what it was before the switch 2 was operated he increases the resistance 6, whereas, if it is less than it was before, he reduces the resistance. The switch S is thrown from one position to the other and the variable resistance 6 varied until the intensity of the sound produced when the current is flowing through the resistance 6 is substantially the,

same as that produced when the current is flowing through the grounded line. When this result is obtained the line man knows he line.

' of wire to the fault can be readily calculated.

a on the other side of the clip.

the clip, that is the ungrounded side, there that the resistance of the line is approximately equal to that of the resistance 6. Since the size of the-line wire is known, the length If the line extends in both directions from the point where the test was made, it is-now necessary to determine the direction. to the trouble. To -do this, the clip 20 is kept on the grounded line and the coil 19 is. removed from around the conductor link 22 and is placed around'the grounded line wire, so that it encircles the line wire in the same manner as it 'previou sl encircled the link 22. The finder coil is p aced around the line wire first on one side of the ch 20 and then ince the current is flowing along the line from the clip 20 to ground, a current will be induced in the coil 19 when the coil is. on the line between the clip 20 and the grounded point, whereas if the coil 19 is on the other side of will beno current flowing fromthe gener ator through the portion of the line embraced by the clip, hence no current will be induced in the coil 30. When current is induced in the coil of-the finder, a sound. is heard in the telephone receivera The presence or absence .of sound in the telephone receiver will be an indication of whether the finder coil is on p the side of the line between the clip 20 and i to the short is then performed in the same manner. as before. The resistance 6 is varied until the intensity of the current induced in the coil of the finder as measured by the intensity of the sound in the receiver, is substantially unchanged when the resistance 6 is substituted for the line resistance by depressing the switch S It should be remembered that now the rheostat reading re resents the combined resistance of the two inc I as that in. the case of a grounded line. The

finder coil is placed around one of the lines,

first .onone side of the clip and then on the Tether. In one case a sound will be heard in "'lgthe receiver and in the other case no sound will be heard. It follows from what has Jar;

been said before, that the fault is along the line in the direction from the clip towards the finder coil'whenithe .finder is on the side of the clip from which the sound is heard.

In testing to determine which one oftwoline conductors is grounded the telephone receiver may be dispensed with and the lamp 11 used as an indicator. The testis performed v I in the same manner as was previously described except the switch S is artially operated so that it closes its first ont contact but not its second front contact. Under those conditions, the lamp 11 is connected across the condensor 10 and. the interrupter contacts 23 are disconnected at the switch S With the clip 21 connected to groundand the clip 20 connected to the grounded line, a

circuit isestablished from ground at the re-' at the clip21. If the clip 20 is connected to the ungrounded line, so such circuit is estab- .lished. The establishment of this circuit is indicated by the lighted condition of the lamp which is in parallel withthe condenser.

the current wave is not very material. At such times the generator is njotshort circuited at contacts 23, the shunting circuit being open at the front contact of switch S and the full output of the generator flows through the lamp 11 and condenser 10 in parallel High resistance shorts such as result when two line wirescross or touch one another very lightly have been a source of great trouble. In such cases, it is generally difficult to determine the line resistance to the fault since the resistance of the fault itself is unknown. This trouble is overcome by providing the outermost left hand contact of the switch S When the switch S is operated to its extreme left hand position, the 'ondenser 10 and the lamp 11 are short circuited and the interrupter contacts 23 are open circuited.

Under those conditions the generator is connected directly-to the line clips 20, 21 and the full output of the generator may be projectedover the line. The large current output from the generator breaks down the resistance at the fault and causes the two line conductors to practically stick together, re-

ducing the resistance to a minimum. The

test for distance to the fault may then be performed in the manner previously explained. r

The line man having determined the direction of the fault and having calculated that the fault'is, let us assume about 20 miles distant, drives out 19 miles instead of 20, just for certainty, and up'on making another test finds that the troubleis'still ahead of him. He can tell however, that the trouble is closer at hand by the increased vohune of the sound in the receiver. The'test now indicates that the fault is, say, one and one tenth miles further ahead. He then proto the fault and repairs the same, makat will,'while the section 63, which is to be ing further tests if the actual trouble is not opened only whenrepairs or replacements readily se'en on approaching its vicinity.

are to be made, is normally held locked by To call the test board man at the telephone the'screws 67. The top 62 may be held closed exchange and notify'him that the trouble has by an ordinary hasp. The cover section 63 is been cleared and the line is now ready for provided with a celluloid window 69 placed to each line, and if the distance to the ex of the lamp may be observed.

change is not too great, the generator is I To the inside of the cover portion 62 there I erated without operating the switch 1, is secured a metal rod 22 about which the thereby projecting ringing current over th finder coil 19 may be clasped. The rod is conline through the condenser 10. If the disnected to the twoinsulated conducting hinges tance to the exchangels too great to ring 64 nd 65, by two conductors placed in through the condenser 10, the switch S 18 grooves on the inner side of the cover.

operated to its extreme left hand position, Through the hinges the rod 22 is connected -Sh 1 1I'Cl11t1I1g he la p 11 n the 0011* to the other parts shown in Figures 1, 2, 3,

denser and placing the entire generator d 4, It may th b en th tthe test to utput a Ij the lin -1 H v ng R j determine which one of two lines is grounded, I'lnging current over the 1111 the h t and also the test for the distance-to a fault, stops rotating-the generator 1 and closes the may b ad ith ut r oving th finder 19 switch S5. He is now placed in talking relaf th a tion with the line, the circuit extending from I the p through the condense! g the plate 70 which is held in two grooves 71,

., hand winding of the coil back Contact one on each side of the box. The telephone sistance 6. 5 In testin to the fault is greater than the number of throughtheresistance than when it is flowbe replacedby a fixed resistance.

her of miles that correspond to the resistance 3, and 4 whereinthereis illustrated the physireceiver c of the fin back receiver, the line clips 21, and the removable.

tact 4, link 22, to the line clip 21 by Way Of handle for turning the generator are carried the back o ta of th SWlteh 2- The h in the chamber to the left of the plate, where- Fy furmshes telklng current to the trans" as the generator 1,'the transmitter 7, inducm tion coil 8, battery 9 and the switch contacts If deslred, the varlable resistance 6 may S S -and S are mountedas a unitary tin I Under ture in the chamber to the right of the plate those conditions the resistance to the fault 7() g y e m y pp x e by Qp g The magneto generator 1 is of standard the swltch S as before. Sin the SlZe 0f the construction and consists ofa number of inline conductors are known, calculation will -t d U h d m n t magnets b eadily h w e y mlles of hue Wire tween the ends of which a coil carrying armarespohd lh-sreslstahce to e -l I the ture is arranged to be rotated. There is prodlstanee 1 the vided a set of contacts 2, 3, and 4, (Fig. 1) tensity of sound in t when the resistance 6 is substituted for the nt f th h ft 5 hi h h ft i line resistance this indicates that the distance moved t dl i th 11 .k ii r upon being rotated. I In additionto the conmiles of line Wire that correspond to the tacts 2, 3, and 4, there is-provided a set of sistance 6. If the intensity of sound in the receiver is less when the current 1s flowing 3a (F 4) normally pressing against the insulating disk 72 upon the shaft that carries ingthrough the. line this indicates that the h armature, but twice, per revolution fault is at a lesser" distance than is the num-' onthe same shaft. The generator unit is secured to the case by two screws (not shown) dlcetes the pp m t dlfiel'ence m e passed thru the bottom of the case into cordistance. res ondin holes drilled in the bottom of the Refe'rencef'may be now had to Figures 2, i t itf 6. 'The different intensity inthe sound incal arrangement of the various parts constituting the test set. The box 60 is made of wood, and is covered with a fibrous protective coating. The box is provided with a cover formed in .two sections 62, and 63. The cover section 62, is hinged to the section 63 by the hinges 64 and 65, while the section by means of a clamp 71. To the top of the magneto thereis fastened a cover plate 76 by means of a bracket 75. An inverted L- shaped plate 77 is secured to the lower side of the cover plate. The plate 77 acts as a support for the contacts controlled-by the The box 60 is divided into two sections by e receiver is'ihcl'eesed arranged to be operated by the-outward contacts 23 consisting of a spring member The condenser10 is secured to the magneto switches S1, and S and for the transmitter further use, the clips 2021 are clamped one opposite the lamp 11, whereby the condition ing contact with conducting projections 23 Y 63 is g to the box y the h g and 7. The springs 78 and 7 9 are insulated from 'is further secured to the bOX y means each other and are fastened tothe plate 77 screws 67 passed through the holes 68. By by means of screws, as may be seen in Fig- 65 this aran'gement the section62 maybe opened ure 4. The springs controlled by the switch S are secured to the plate 77 in a, similar manner, as shown in Figure 2. A section 85 is punched in the cover plate andthe metal is bent down at 85' to form a support for the springs 80,81, and 82 of the switch S The induction coil 8 is mounted on the lower side of the cover plate 76 in a position shown in Figures 2 and 4. Two L -shaped metal strips 86, secured to the cover plate,

support the insulating terminal block 87 on which are mounted the terminals 12 to 17, The screws passing thru the insulating block 88, secure it and the bracket 7 5 to the cover plate. The spring terminal clips 89, maintain the the battery 9 against the bracket 90,

the bracket being secured to the cover plate. 1

The lamp 11 is "mounted on the cover plate in any well known manner. There is also provided two binding posts 91, insulated from thecover plate, to which are connected leads from therheostat 6. a When the push button S shown in Figure 4 is pushed with the'flat portion of the thumb until the thumb encounters the box, the right hand back contact shown in Figure 1 will be opened and the middle front contact will be closed, but the outer left front contact will still be open. If the push button S is pushed in further, for instance with the tip of the thumb, the outer left front contact will also be closed.

When it is desired to use thew-transmitter 7 the lineman may findit rather inconvenient to hold the box with the transmitter 7 (Fig. 2) before him. Under su'cliconditions it isfrequently quite convenient 'to talk directly into the left hand chamber of the box, the

"cover 62 being open. To facilitate this, the

plate 7 O is provided with a number of small holes through which sound may pass. It

' is found that the transmitter 7, when mounted as shown in Figure 2, responds very satisfactorily to sound waves reaching it by way of the-holes in the plate 70.

What is claimed is: 1. .A line test set wherein a telephone receiver and a. finder coil are connected in series across two line clips, 2. generator, a switch, and connections controlled by the switch for connecting the generator in place of the telephone and finder coil. and for connecting the telephone .and the finder coil in a closed loop. 7

2. A line test set wherein a telephone receiver and a finder coil'are connected in series across two lineclips, a generator, ,9.

switch operated upon the operation of the generator for connecting the generator across the line clips in place of the telephone and finder coil and for connecting the "telephone and the finder coil in a-closed loop.

. 3. Ina line test set, a pair of line clips, a telephone receiver normally connected across said line clips, a generator normally disconnected from one of the line clips, a finder coil, and means controlled by the generator finder, and for connecting the generator across the line clips. 4. A line test set mounted in a case and including means for connecting the set to a line to be tested, an inductance coil, 2. conducting link permanently mounted within the case and connected in serieswith said means, said coil being normally inductively coupled with said link. a

5. A line test set mounted in a case and including a pair of line clips to be connected to line to be tested, an inductance coil removably held in said case and connected with the rest of the set by flexible leads, a conducting link within the case connected in series with said clips, said coil being normally inductively coupled with said link, a

testing circuit including said link and said line to be tested, a variable artificial line within the case, means for establishing a circuit either to the line to be tested or to the artificial line, and induction means for comparing the current flow in the two lines.

8. A line test set including means for connecting the set to a line to be tested, a conducting link and a variable calibrated resistor, means for connecting the conducting link in series with the line tdbe' tested or with said resistor, and an inductance coil adapted to be mounted in inductive relationship with said conducting link.

9. Aline test set mounted in a case and including a pair of line clips to be connected to a line to be tested an inductance coil, a

conducting link within the case connected in series with said clips, said coil being normally inductively coupled with said link, a re sistor, and means for connecting said resistor in said series circuit in place of said clips.

10. including means for connecting the set to a line to bertested, a resistor, a conducting linl' within the case-normally connected in series with said means, means for substitutingthe resistor for said first means in said series circuit, and an inductance co l removably held in said case and connected with the rest A- line test set mounted in a case and.

of the set by flexible leads, said coil being p normally inductively coupled with said link. 11. A line test set mounted in a case and including means for connecting the set a'line to be tested, a resistor, a conducting link within the case connected in series with said means, means for substituting the resistor for the clip in said series circuit, an inductance coil normally inductively coupled with said link, and a telephone receiver connected to detect current flow in said inductance coil. V :12. A line test set including a magneto generator having mounted thereon to form an integral unit, a switch, a condenser, a battery, and a telephone transmitter, a box divided into two compartments in one of which the unit is mounted, and a telephone receiver, an inductance coil and a line clip electrically connected with said unit carried in the other compartment.

13. A test set case having mounted therein a generator to which is secured a tele hone transmitten'said case having a plurallty of small holes formed therein opposite the transmitter through which sound may pass to the I transmitter, a partition dividing the case into two compartments, said partition having formed therein a number of small holes through which sound may'pass to the transmitter. a v 14. A finder having an iron core and a winding therefor mounted between two spring pressed jaws of magnetic material, one

of said jaws having a groove therein in which groove s placed one of the incoming conduc- J tors to the coil, a protecting sheet of magnetic an incoming lead, andscrews in the termi- D1111 block for holding the incoming leads in p ace. 7

17. In a line test set, a pair of line clips, 0. receiver and a condenser normally connected to said line. clips, a generator, means eflfective' 18. In a line test set, a pair of line clips, a i 7 receiver and a condenser normally, connected to sa1d lme chps, a generator, means efie'ctive upon theoperat on of the generator for disconnecting the receiver from the line clips and Y for connecting the generator tothe line clips in series with the condenser, and means for shunting the condenser.

19. In a line test set, a pair oiline clips,

a receiver and a-conde'nser normally connected to said line clips, a generator, means effective updn the operation of the generator for disconnecting the receiver from the line clips periodically short-circuiting' the generator,

and for connectingthe generator tothe line clips in series with the condenser, means for and means for preventing the .last named.

means from being effective and for shunting the condenser."

20. Ina line test set, a pair of line clips,

a receiver and a condenser normally connected to said line clips, agenerator, means efiecmaterial extending along the jaw from the tive upon the operation of the generator for coil to the point where the two jaws are pressed together, said sheet covering the groove containing the wire.

15. A finder consisting of a clip having two pivoted vjaws of magnetic material pressed against each other by. a spring, an obong coil having an iron core mounted between said jaws, said core being secured to one of said jaws 'so as to be included in a series magnetic circuit with both of said jaws and spaced from the pivot oint of the jaws,-

so that the clip may be p aced around a wire to be tested by opening the jaws and slipping the clip) over the wire until the .wire is 1n the space etween the coil and pivot point, and upon closing the'jaws the clip is retained around the wir I V 16. A finder consisting of a pair of pivoted jaws, acoil mounted betweensaid .jaws, sai djaws being extended to form two handles for opening the jaws, aterminal block consisting disconnecting the receiver from the line clips and .for connecting the generator to the line clips in series with the condenser, a lamp, and

a two-position key for bridging the lamp across the condenser when operated to its first position and for shunting the lamp and the leacondenser when operated to its second position.

21. A line test set mounted in a case, an ar-" tificial line within the case, means for alternatively establishinga flow of current in the '22. A line test set comprising a generator, a transmitter mounted on the generator, and a case having a partition dividing the case into two compartments, the first compartment he'- ing adapted to house thegenerator and transmitter unit, said partition having holes through which sound directed into the second of a-cylindrical insulating casing containing compartment may pass to the transmitter.

three metal slugs insulated from each other;

said'terminal block being secured to one hanhand e and one slug, the other two slugs each having two holes drilled through the easing into the slug, one of said two holes being for the first compartment hinged to the case,

adapted to receive a permanent connection to'the-coil, and the other adaptedto receive 23. A line test set case comprising two compartments,- the first compartment adapted to and a second cover for the secondcompa-rt- .mentzhi'nged to the firstv cover.

24. for .a line test set comprising a generator, a receiver,'and a finder coil, said case comprising two compartments, the first compartment adapted to house the generator, and the second compartment adapted to serve as a space for the receiver, a cover for the first compartment hinged to said case, and a second cover for the second compartment hinged to said first cover, said second cover having a pocket adapted to serve as a space for the finder coil.

25. A line. test set mounted in a case, a finder coil, a cover hinged to the case by means of two electrically insulated hinges, a conducting link mounted in said cover and adapted to support said finder coil, said conductor link being electrically connected to the test set through said hinges. 1

26. A finder consisting of a clip having two spring jaws pivoted at one end, a coil having an iron core, one end of said core being secured to the free end of one of said jaws, the other end of'said core .bein adapted to engage the free end of the other ofsaid jaws, and 'a magnetic circuit closed by said jaws including said core and the sections of said jaws between the respective points of contact with said core and the pivoted end.

27. In a line test set, a pair of line clips, a condenser, a receiver normally connected across said line clips. in series with said condenser, a generator, a finder coil, and means controlled by the generator for'disconnecting said receiver from said line clips and connecting it across said finder coil and for connecting said generator across said line clips in series with said condenser.

28. In a line test'set, a pair of line clips, a condenser, an induction coil, a receiver. normally bridged across said line clips in series with said line clips and a winding of said induction coil, a generator, a finder coil, and means controlled by said generator for disconnecting said receiver from said line clips, said condenser al ld said induction coil winding and for connecting it across said finder coil, and for bridging said generator across said line clips in series with said condenser. Y 29. In a test set including means for connecting the setv to outside conductors to be tested, a conducting link connectedin series with said means, an inductance coil normally inductively coupled with said link, and means for testing conductors with said inductance coil in either its normal position or inductively, coupled with one of the conductors under test.

30. In a test set including means for connecting the set to line conductors to be tested, a conducting link connected in series with said means, an inductance coil normally inductively coupled with said link, means for performing certain tests on the line conductors with said inductance coil in normal position, and means for performing certain other tests on the line with said inductance coil inductively coupled with one of the conductors under test.

31. A line test set mounted in a case and includin means for connecting the set to the line con uctors to be tested, a conducting link within the case connected in series with said means, an inductance coil adapted to be inductively coupled with a line conductor under test but normally carried in the case in inductive relation with said link, and means for testing a line without removing said inductance coil from the case.

32. In a line test set, an induction coil, a primary winding for said coil permanently mounted in said set, a secondary winding normally associated with said primary winding, arrangements whereby said secondary winding may be readily removed from the set and placed in inductive relation to outside conductors, and a receiver connected to said secondary winding when the same is in use in either case. a

33. In a line test set, a finder coil for use outside the set and connected to the same by flexible conductors, a compartment inside the set for storing said coil, and a conductor in said compartment with which the coil is inductively coupled when stored in the compartment.

34. A line test set including a magneto generator having mounted thereon to form an integral unit, a switch, a condenser, a battery, and a telephone transmitter, a box divided :into two compartments in one of which the unit is mounted, and a conductin link comprisin a rigid conductor electrica y connected wit said unit mounted in the other compartment.

In witness whereof, I hereunto subscribe my name this 2d day of July, A. D. 1927.

CLARENCE A. ANDERSON. I 

